Posted on Wednesday, August 07, 2013 8:01 PM
Following cardio or a weight lifting session, your body continues to use oxygen at a higher rate than it did prior to exercise. This sustained oxygen consumption is known as excess post-exercise oxygen consumption (EPOC). The phrase EPOC has been used to describe numerous events that occur while the body returns to homeostasis. During EPOC, the body is in the process of returning to a pre-exercise state, so it consumes oxygen at a higher rate. This means that calories are being burned at a higher rate.
Four things occurs during EPOC:
1) Replenishment of Energy Resources: Replenishment ensues for the immediate source of energy, known as the phosphagen system, which is includes creatine phosphate and ATP (adenosine triphosphate). In addition, lactate, a molecule produced while performing intense exercise, is being converted to pyruvate for fuel utilization. The body is also replenishing the glycogen stores that were depleted during the workout
2) Re-oxygenation of Blood and Restoration of Circulatory Hormones
During exercise metabolism, sizeable quantities of oxygen are used to break down food substrates for energy. Consequently, the body continues to utilize energy following exercise to re-oxygenate the blood. In addition, in the post-exercise period, the body restores the levels of circulatory hormones, which increased during exercise, to normal.
3) Decrease in Body Temperature:
As energy is released from the muscle tissues of the body, during exercise, heat is produced, so during EPOC, the body must burn calories in order to return to it’s normal temperature.
4) Return to Normal Ventilation and Heart Rate: Energy expenditure is greatly elevated as the body rapidly returns to a normal breathing rate. Heart rate is also returning to a pre-exercise rate.
Evidence indicates that interval training (HIIT) has a distinct effect on EPOC. Also, it appears that weight training produces greater EPOC responses than aerobic exercise such as jogging. HIIT disturbs homeostasis more so than cardio at moderate intensity resulting in more calorie expenditure to restore the body to homeostasis. Mechanisms that cause the higher EPOC observed in resistance exercise include elevated blood lactate, and an increase in circulating catecholamines (epinephrine and norepinephrine) and anabolic hormones.